Abstract : The built-in electrical check multi-frequencies charge injection allows testing the entire measurement chain, including the microphone. It consists in injecting a sinusoidal charge 1 or 2 levels into the microphone membrane, at selected frequencies. The principle is to collect reference values initialisation stage and to check over time that the deviation between the reference values and the measured values does not exceed a maximum predefined deviation value. A multiple-frequency check offers the advantage of a better assessment of a possible degradation of the microphone membrane as well as the electronic components. The checking procedure lasts from 10 to 30 seconds and occurs between two measurements, so as to make their validation easier. The purpose of the paper is to describe the results obtained for different types of defaults in the measurement chain.